I have many times linked two XLR cables, and while theoretically there is loss, I suspect that unless you were conducting side by side comparison of, say, 2x1.5 versus 1x3 you would not hear a difference, and perhaps not even in direct comparison.
From the myriad cable tests and systems I have built you are likely to encounter far more difference in moving between brands and models of XLR and RCA cables than to link two XLR to achieve equivalent length of a single cable.